Motion picture camera with zoom lens

ABSTRACT

A motion picture camera wherein the lever which is movable to change the focal length of the zoom lens controls a carriage which moves a system of magnifying lenses into registry with the eyepiece of the through-the-lens viewfinder so that the user can see a greatly enlarged portion of the image prior to and during manipulation of the focusing ring. The lever places the magnifying lenses into registry with the eyepiece of when the zoom lens is adjusted for maximum focal length. A leaf spring in the lens mount biases the lever to a position in which the lever permits movement of the magnifying lenses out of registry with the eyepiece and places a second system of lenses into registry with the eyepiece. The second system of lenses does not appreciably magnify the viewed image.

United Sta Loewe MOTION PICTURE CAMERA WITH ZOOM LENS Appl. No.: 63,097

Foreign Application Priority Data Aug. 16, 1969 Germany ..P 19 41 789.]

US. Cl. ..95/44 R, 88/1 .5 NR, 350/183, 350/184, 350/187, 352/140lnt.Cl. ..G03b 3/00,G03b 13/16, G03b 13/26 Field of Search ..95/44, 42;352/140; 350/183, 350/184, l87;88/1.5 NR

[ 51 May 30, 1972 [56] References Cited UNITED STATES PATENTS 3,083,6284/1963 Tsugawa ..88/l.5 UX

Primary Examiner-Samuel S. Matthews Assistant Examiner-Richard A.Wintercom Attorney-Michael S. Striker A motion picture camera whereinthe lever which is movable to change the focal length of the zoom lenscontrols a carriage which moves a system of magnifying lenses intoregistry with the eyepiece of the through-the-lens viewfinder so thatthe user can see a greatly enlarged portion of the image prior to andduring manipulation of the focusing ring. The lever places themagnifying lenses into registry with the eyepiece of when the zoom lensis adjusted for maximum focal length. A leaf spring in the lens mountbiases the lever to a position in which the lever permits movement ofthe magnifying lenses out of registry with the eyepiece and places asecond system of lenses into registry with the eyepiece. The secondsystem of lenses does not appreciably magnify the viewed image.

ABSTRACT 10 Claims, 2 Drawing Figures PMented May rm, mm 3,665,834

FIGQ

INVENTOR 7 Richard LOEWE his ATTORNEY MOTION PICTURE CAMERA WITH ZOOMLENS BACKGROUND OF THE INVENTION The present invention relates toimprovements in motion picture cameras with zoom lenses, and moreparticularly to improvements in motion picture cameras with zoom lensesand through-the-lens viewfinders.

In motion picture cameras with zoom lenses and throughthe-lensviewfinders, the focussing is carried out when the operator of thecamera sees in the viewfinder a greatly magnified image of the subjector scene, namely, when the zoom lens is adjusted for maximum focallength. This insures more accurate focussing. It was found, however,that the magnification by the viewfinder objective cannot invariablyinsure focussing with requisite accuracy. Therefore, certain motionpicture cameras embody various auxiliary focussing devices or focussingaids, such as magnifying lenses, sharpness indicators or the like. Suchauxiliary focussing devices can be moved into the beam of light whichenters the eyepiece of the viewfinder at the time when the zoom lens isset for maximum focal length. The operator is then in a position toaccurately determine and/or focus to insure maximum sharpness while thezoom lens furnishes a greatly enlarged viewfinder image.

In order to insure that the focussing is carried out when the zoom lensis set for maximum focal length, certain motion picture cameras embodymeans for automatically adjusting the zoom lens for maximum focal lengthas soon as the auxiliary focussing device is moved into the path oflight entering the viewfinder eyepiece. Reference may be had to GermanPat. No. 1,197,745. A drawback of such cameras is that theirmanipulation is rather complicated because they must be provided withtwo discrete actuating means, namely, one for moving the auxiliaryfocussing device into or from the path of light which enters theeyepiece of the viewfinder and the other for selection of a shorterfocal length. Thus, in order to properly focus, the operator of the justdescribed conventional motion picture camera must manipulate a firsthandgrip member so as to move the auxiliary focussing device (e.g., amagnifying lens) into the path of light entering the eyepiece of theviewfinder, the focussing ring is thereupon manipulated to carry out thefocussing operation, the first handgrip member is thereupon manipulatedto move the auxiliary device out of the light path, and a secondhandgrip member is manipulated to select a shorter focal length. Thehandgrip members can transmit motion by way of suitable mechanicaltrains or by actuating electric switches which start or arrest one ormore motors in the camera.

SUMMARY OF THE INVENTION An object of the invention is to provide amotion picture camera with a zoom lens and with a through-the-lensviewfinder wherein a single actuating member suffices to assist inaccurate focussing and also to select an appropriate focal length.

Another object of the invention is to provide a motion picture camerawherein the auxiliary focussing device or devices which serve asfocussing aids need not be manipulated by hand but automatically assumean optimum position with reference to the eyepiece of the viewfinderwhen the operator of the camera is ready for focussing.

An additional object of the invention is to provide a motion picturecamera wherein the actuating means for adjusting the focal length of thezoom lens is automatically ready to change the focal length in responseto even minimal displacement of its input member as soon as thefocussing operation is completed.

A further object of the invention is to provide a novel operativeconnection between one or more focussing aids in a motion picture cameraand the actuating means for changing the focal length of the zoom lens.

Still another object of the invention is to provide an operativeconnection of the above outlined character which is simple compact andrugged, and which can be installed in existing types of motion picturecameras with minimal alterations in their basic design.

The improved motion picture camera comprises a picture taking lens ofvariable focal length, actuating means movable between a plurality ofpositions to thereby change the focal length of the lens, a viewfinder,focussing means, an auxiliary focussing device movable into and out ofregistry with the viewfinder, and an operative connection between theactuating means and the auxiliary focussing device for moving the latterinto registry with the viewfinder within a predetermined range ofpositions of the actuating means. The viewfinder is preferably of athrough-the-lens viewfinder and the auxiliary focussing device maycomprise a system of magnifying lenses which are movable into and out ofregistry with the eyepiece of the viewfinder.

The auxiliary focussing device can be held in registry with theviewfinder when the actuating means assumes a range of positions each ofwhich corresponds to the maximum focal length of the picture takinglens.

The camera preferably further comprises means for biasing the actuatingmeans to a given position in which the operative connection is free tomove the auxiliary focussing device out of registry with the viewfinder.Such biasing means may comprise a leaf spring bearing against a leverwhich forms part of the actuating means and is turnable in a slotprovided in the tubular mount for the picture taking lens.

The operative connection may comprise a cam and follower arrangementwhich cooperates with a spring to effect movements of a carriage for theauxiliary focussing device between two end positions in one of which theauxiliary focussing device registers with the eyepiece of the viewfinderand in the other of which the eyepiece registers with another system oflenses which do not appreciably enlarge the viewed subject or scene.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved motion picture camera itself, however, both as to itsconstruction and its mode of operation, together with additionalfeatures and advantages thereof, will be best understood upon perusal ofthe following detailed description of certain specific embodiments withreference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a fragmentary longitudinalvertical sectional view of a motion picture camera which embodies theinvention; and

FIG. 2 is a transverse vertical sectional view as seen in the directionof arrows from the line lI-II of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a portion of amotion picture camera having a housing whose front wall 1 supports apancratic picture-taking zoom lens 2. The front portion of the tubularmount 6 for the lens 2 supports a knurled or milled focussing ring 3having an index 4 which can be moved into registry with the graduationsof a distance scale 5 of the lens mount 6. The lens mount is fixed tothe front wall 1 of the housing and accommodates a cylindrical sleeve 7(FIG. 2) which is rotatable about its axis. The sleeve 7 is coupled withthe optical elements of the picture-taking lens 2 and its rotationcauses such elements to move in the direction of the optical axis. Theconnection between the sleeve 7 and the optical elements preferablycomprises cam grooves and followers. Such axial displacement of theoptical elements effects appropriate changes in focal length of the lens2. The actuating means for changing the focal length of the lens 2further comprises a handgn'p member or lever 9 which extends radiallyoutwardly through a circumferentially extending slot 8 of the lens mount6. The sleeve 7 has an index 10 which is observable in the slot 8 and ismovable into registry with the graduations of a scale 11 on the lensmount 6.

A partially light transmitting mirror 13 is placed at an angle of 45into the path of incoming scene light to deflect a certain percentage ofsuch light against a fully reflecting mirror 14. The latter directs thetwice deflected light beam into the eyepiece 16 of a through-the-lensviewfinder. An optical unit is disposed between the eyepiece l6 and themirror 14.

The optical unit 15 comprises two sets of lenses 18, 19 which arerespectively installed in cylinders 17, 17a. These cylinders are securedto a carriage which is reciprocable at right angles to the optical axisof the eyepiece 16. The carriage 20 is movable between first and secondpositions in which the eyepiece 16 respectively registers with thelenses 18 and 19.

The optical characteristics of the lenses 18 and 19 are such that thelenses 18 at most effect an insignificant magnification of the image andthat the lenses l9 efl'ect a substantial magnification of the image orof a portion of the image. Therefore, the lenses 19 are used asauxiliary focussing means or focussing aid when the actuatingmeans 7,9assumes a position corresponding to the maximum focal length of the lens2. This facilitates accurate focussing by means of the ring 3.

In order to reduce the number of manipulations which are necessary toinsure sharp focussing, the optical unit 15 is coupled with the lever 9of the actuating means for the zoom lens 2 in such a way that the lenses19 are automatically moved into registry with the eyepiece 16 when thelever 9 assumes a predetennined range of angular positions. In theillustrated embodiment, the lenses 19 are in registry with the eyepiece16 when the lever 9 assumes a position within the angle alpha shown inFIG. 2. The lever 9 assumes such positions when the zoom lens 2 isadjusted for maximum focal length. Such maximum focal length remainsunchanged when the lever 9 moves within the angle alpha.

The operative connection between the actuating means 7, 9 and thecarriage 20 for the cylinders 17, 17a of the lenses 18, 19 comprises arotary ring-shaped cam 21 which is rigid with the sleeve 7 and has a camface provided with a lobe adapted to displace a motion transmittingfollower pin 23 which is guided in a partition 22 of the housing. Thepartition 22 has a window 22a through which the light, which has passedthrough the mirror 13, can reach an unexposed frame of the motionpicture film 12. The right-hand end of the follower pin 23 abuts againstthe lower arm of a bell crank lever 24 which is pivotable on a fixed pin25 and is biased in a clockwise direction by a helical spring 27 whichis coupled to the carriage 20 and is attached to a post 27a of thehousing. The carriage 20 has a projection 26 which abuts against theupper arm of the lever 24 under the action of the spring 27. Thecarriage further has elongated slots 20a receiving guide pins 20b whichare mounted in the housing. The spring 27 can bias the lefthand end ofthe follower pin 23 against the face of the cam 21 by way of thecarriage 20, projection 26 and lever 24. Stops (not shown) are providedto arrest the carriage 20 in the two end positions in which the eyepiece16 respectively registers with the lenses 18 and 19.

The camera further comprises resilient means for biasing the lever 9toward a given position. Such resilient means comprises a leaf spring 28which is mounted in the interior of the lens mount 6 and biases thelever 9 downwardly, as viewed in FIG. 1, toward the lower end of theportion alpha of the path. Thus, the lever 9 must be pivoted by hand inorder to move the lenses 19 into register with the eyepiece 16. When thelever 9 is released while it assumes a position within the rangeindicated by the angle alpha, it automatically moves under the action ofthe spring 28 and assumes that given angular position in which itimmediately begins to change the focal length if it turns in a clockwisedirection, as viewed in FIG. 2. The lobe of the cam 21 then moves awayfrom the follower pin 23 so that the spring 27 is free to contract andto move the carriage 20 to its lower end position in which the lenses 18register with the eyepiece 16. The leaf spring 28 has a plate-likeportion 29 which extends into the slot 8 of the lens mount 6 and intothe path of movement of the lever 9. That portion of the slot 8 in whichthe lever 9 advances while it assumes a position within the angle alphais wider than the remaining part of the slot and the lens mount definesa shoulder or stop 30 against which the portion 29 of the spring 28abuts when the lever 9 is moved beyond the range of positions within theangle alpha.

The operation:

In order to properly focus, the user of the camera moves the lever 9 tothe position shown in FIG. 1 in which the lever assumes a positionwithin the range identified by the angle alpha. This necessitatespivoting of the lever 9 in the direction indicated by the arrow 31 (FIG.2) whereby the stem of the lever engages the portion 29 of the spring 28and moves it away from the shoulder 30 to stress the spring. The lever 9can be moved all the way to its extreme position in which the portion 29of the spring 28 abuts against the surface at the lefthand end of theslot 8, as viewed in FIG. 2. As the lever 9 engages and pushes theportion 29 of the spring 28, the lobe of the cam 21 (which rotates withthe lever 9 because it is rigid or integral with the sleeve 7) engagesand shifts the follower pin 23 which pivots the lever 24 in acounterclockwise direction against the opposition of the spring 27. Thecarriage 20 moves upwardly and places the auxiliary focussing device(lenses 19) into registry with the eyepiece 16 of the viewfinder. Suchposition of the carriage 20 and lenses 19 is shown in FIG. 1. The userthereupon rotates the focussing ring 3 until the eye looking into theeyepiece l6 sees a sharp image of a sharply defined portion of theimage. This completes the focussing operation.

The user thereupon leaves the ring 3 in the selected position and canpivot the lever 9 to any desired position to select an appropriate focallength. The lobe of the cam 21 moves beyond the follower pin 23 as soonas the portion 29 of the leaf spring 28 reengages the shoulder 30 of thelens mount 6. From there on, the focal length changes because thepositions of the lever 9 are outside of the range indicated by the anglealpha. Also, as the lobe of the cam 21 moves away from the follower pin23, the spring 27 is free to contract so that the carriage 20 movesdownwardly and returns the lenses 18 into registry with the eyepiece 16.Thus, the user sees the subject of scene in actual size or on a slightlyenlarged scale.

If the user wishes to make exposures with maximum focal length, thelever 9 is simply released after the user completes the focussingoperation. This enables the spring 28 to dissipate energy until itsportion 29 engages the shoulder 30 whereby the lever 9 is pushed to thegiven position at the lower limit of the range of positions within theangle alpha; such given position still corresponds to the maximum focallength. Also, the lenses 18 automatically return into registry with theeyepiece 16 because the spring 27 can contact as soon as the lobe of thecam 21 moves beyond the adjacent end of the follower pin 23. This takesplace when the portion 29 of the leaf spring 28 reaches the shoulder 30.

An important advantage of the improved motion picture camera is that theauxiliary focussing device (i.e., the lenses 19) need not be moved by aseparate handle, lever, knob, switch or other actuating means. Thisauxiliary focussing device is moved into and out of registry with theeyepiece 16 of the viewfinder in automatic response to manipulation ofthe lever 9 for the zoom lens 2. It is clear that the lever 9 can bereplaced by a knob or pushbutton which controls a switching arrangementfor a motor capable of adjusting the zoom lens to change the focallength. The manipulation of the improved camera is simpler than that ofaforedescribed conventional cameras wherein the auxiliary focussingdevice or devices must be moved into and away from registry with theeyepiece of the viewfinder by discrete actuating means. Therefore, thecamera of my invention can be readily operated by unskilled lbeginnersor by inexperienced amateur photographers. Since the spring 28 alwaysbiases the lever 9 to a given position which still corresponds tomaximum focal length of the zoom lens 2 but in which the lever 9immediately begins to change the focal length when moved clockwise, asviewed in FIG. 2, the user sees an image which is not enlarged at all oris enlarged only negligibly (lenses 18) as soon as the lever 9 isreleased as well as when the angular movement of the lever 9 actuallyresults in a change of focal length. Consequently, the user of thecamera need not be concerned with the positioning of lenses l8 and 19because the lenses 18 are invariably in registry with the eyepiece 16when the lever 9 is released as well as when the lever 9 is moved forthe purpose of changing the focal length. In the course of one or moreexposures, the user of the camera should see the entire image, not onlyan enlarged portion of such image; therefore, the eyepiece 16 shouldregister with the lenses 18 whenever the camera is in the process ofmaking one or more exposures.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic andspecific aspects of my con tibution to the art and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended.

1. In a motion picture camera, a combination comprising an objectivelens of variable focal length; actuating means movable between aplurality of positions to thereby change the focal length of said lenswhile moving between at least some of said positions; an eyepiecereceiving light which passes through said objective lens focussingmeans; focussing aid means movable into and out of registry with saideyepiece; and an operative connection between said actuating means andsaid focussing aid means for moving the latter into registry with saideyepiece within a predetermined range of positions of said actuatingmeans preparatory to actuation of said focussing means and to move saidfocussing aid means out of registry with said eyepiece when saidactuating means leaves said range of positions.

2. In a motion picture camera, a combination comprising a picture takinglens of variable focal length; actuating means movable between aplurality of positions to thereby change the focal length of said lenssaid positions; a through-the-lens viewfinder; focussing means;focussing aid means movable into and out of registry with saidviewfinder; and operative connection between said actuating means andsaid focussing aid means for moving the latter into registry with saidviewfinder within a predetermined range of positions of said actuatingmeans.

3. A combination as defined in claim 2, wherein said operativeconnection comprises means for moving said focussing aid means out ofregistry with said viewfinder when said actuating means leaves saidrange of positions.

4. In a motion picture camera, a combination corr prising a picturetaking lens of variable focal length; actuating means movable between aplurality of positions including two end positions to thereby change thefocal length of said lens while moving between at least some of saidpositions; a viewfinder; focussing means; focussing aid means movableinto and out of registry with said viewfinder; and an operativeconnection between said actuating means and said focussing aid means formoving the latter into registry with said viewfinder within apredetermined range of positions of said actuating means, said range ofpositions being adjacent to one of said end positions.

5. A combination as defined in claim 4, wherein said range of positionscorresponds to the maximum focal length of said lens.

6. A combination as defined in claim 5, further comprising means forbiasing said actuating means to a given position outside of said range,said given position corresponding to the maximum focal length of saidlens.

7. A combination as defined in claim 6, further comprising a housing anda tubular lens mount on said housing, said means for biasing comprisinga spring provided in said mount and bearing against a portion of saidactuating means when the latter assumes a position within said ran e 8.In a motion picture camera, a com matron compnsmg a picture taking lensof variable focal length; actuating means movable between a plurality ofpositions to thereby change the focal length of said lens while movingbetween at least some of said positions; a viewfinder; focussing means;focussing aid means movable into and out of registry with said viewfinder; and an operative connection between said actuating means andsaid focussing aid means for moving the latter into registry with saidviewfinder within a predetermined range of positions of said actuatingmeans, said operative connection comprising a carriage for saidfocussing aid means and a cam-and-follower drive receiving motion fromsaid actuating means and arranged to move said carriage to a position inwhich said focussing aid means registers with said viewfinder.

9. A combination as defined in claim 8, further comprising means forbiasing said carriage to a second position in which said focussing aidmeans is out of registry with said viewfinder.

10. In a motion picture camera, a combination comprising a picturetaking lens of variable focal length; actuating means movable between aplurality of positions to thereby change the focal length of said lenswhile moving between at least some of said positions; a through-the-lensviewfinder having an eyepiece; focussing means coaxial with said lens;focussing aid means movable into and out of registry with said eyepieceof said viewfinder; and an operative connection between said actuatingmeans and said focussing aid means for moving the latter into registrywith said eyepiece of said viewfinder within a predetermined range ofpositions of said actuating means.

1. In a motion picture camera, a combination comprising an objectivelens of variable focal length; actuating means movable between aplurality of positions to thereby change the focal length of said lenswhile moving between at least some of said positions; an eyepiecereceiving light which passes through said objective lens focussingmeans; focussing aid means movable into and out of registry with saideyepiece; and an operative connection between said actuating means andsaid focussing aid means for moving the latter into registry with saideyepiece within a predetermined range of positions of said actuatingmeans preparatory to actuation of said focussing means and to move saidfocussing aid means out of registry with said eyepiece when saidactuating means leaves said range of positions.
 2. In a motion picturecamera, a combination comprising a picture taking lens of variable focallength; actuating means movable between a plurality of positions tothereby change the focal length of said lens said positions; athrough-the-lens viewfinder; focussing means; focussing aid meansmovable into and out of registry with said viewfinder; and operativeconnection between said actuating means and said focussing aid means formoving the latter into registry with said viewfinder within apredetermined range of positions of said actuating means.
 3. Acombination as defined in claim 2, wherein said operative connectioncomprises means for moving said focussing aid means out of registry withsaid viewfinder when said actuating means leaves said range ofpositions.
 4. In a motion picture camera, a combination comprising apicture taking lens of variable focal length; actuating means movablebetween a plurality of positions including two end positions to therebychange the focal length of said lens while moving between at least someof said positions; a viewfinder; focussing means; focussing aid meansmovable into and out of registry with said viewfinder; and an operativeconnection between said actuating means and said focussing aid means formoving the latter into registry with said viewfinder within apredetermined range of positions of said actuating means, said range ofpositions being adjacent to one of said end positions.
 5. A combinationas defined in claim 4, wherein said range of positions corresponds tothe maximum focal length of said lens.
 6. A combination as defined inclaim 5, further comprising means for biasing said actuating means to agiven position outside of said range, said given position correspondingto the maximum focal length of said lens.
 7. A combination as defined inclaim 6, further comprising a housing and a tubular lens mount on saidhousing, said means for biasing comprising a spring provided in saidmount and bearing against a portion of said actuating means when thelatter assumes a position within said range.
 8. In a motion picturecamera, a combination comprising a picture taking lens of variable focallength; actuating means movable between a plurality of positions tothereby change the focal length of said lens while moving between atleast some of said positions; a viewfinder; focussing means; focussingaid means movable into and out of registry with said view finder; and anoperative connection between said actuating means and said focussing aidmeans for moving the latter into registry with said viewfinder within apredetermined range of positions of said actuating means, said operativeconnection comprising a carriage for said focussing aid means and acam-and-follower drive receiving motion from said actuating means andarranged to move said carriage to a position in which said focussing aidmeans registers with said viewfinder.
 9. A combination as defined inclaim 8, further comprising means for biasing said carriage to a secondposition in which said focussing aid means is out of registry with saidviewfinder.
 10. In a motion picture camera, a combination comprising apicture taking lens of variable focal length; actuating means movablebetween a plurality of positions to thereby change the focal length ofsaid lens while moving between at least some of said positions; athrough-the-lens viewfinder having an eyepiece; focussing means coaxialwith said lens; focussing aid means movable into and out of registrywith said eyepiece of said viewfinder; and an operative connectionbetween said actuating means and said focussing aid means for moving thelatter into registry with said eyepiece of said viewfinder within apredetermined range of positions of said actuating means.